It was confirmed today that R.B.I. Baseball 18 was approved by Nintendo and will be released digitally for Switch in the US on June 14. Europe and Japan will also be getting digital releases the following week, with a retail release sometime after.
As was announced on Twitter:
We're continuing to work with our partners to finalize a distribution date to all North American retailers. We will update you with that information as soon as it is confirmed. We're sorry for the delays you have experienced. Thank you for your patience and support.
— R.B.I. Baseball 18 (@RBIGAME) June 8, 2018